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Abstract:

A template chuck includes multiple zones to provide 1) an imprint bend
optimized to provide high curvature and provide contact at middle radius
of substrate and/or, 2) separation bend zone with an increased free span
zone and high crack angle.

Claims:

1. A nano-imprint lithography method, comprising:imprinting polymerizable
material positioned on a substrate with a template forming a patterned
layer on the substrate, the template coupled to a chuck providing the
template with a first free span length; and,separating the template and
the patterned layer, the chuck providing the template with a second free
span length prior to separation.

2. The nano-imprint lithography method of claim 1, wherein the first free
span length is less than the second free span length.

3. The nano-imprint lithography method of claim 1, wherein the second free
span length is configured to reduce the magnitude of force needed to
separate the template from the patterned layer.

4. The nano-imprint lithography method of claim 1, wherein the chuck
includes four zones: a separation outer bend zone, an imprint outer bend
zone, a back pressure zone, and an inner bend zone, the separation outer
bend zone cincturing the imprint outer bend zone which cinctures the back
pressure zone which cinctures the inner bend zone.

5. The nano-imprint lithography method of claim 4, wherein a pump system
controls pressure within each zone during the imprinting step and the
separation step.

6. The nano-imprint lithography method of claim 5, wherein prior to
imprinting, the pump system provides the imprint outer bend zone and the
inner bend zone in a vacuum state, and the back pressure zone in a
pressure state, such that template forms a toroidal imprint shape having
the first free span length.

7. The nano-imprint lithography method of claim 6, wherein the toroidal
imprint shape provides deflection of the template symmetric about a
middle radius of the substrate during imprinting.

8. The nano-imprint lithography method of claim 6, wherein the imprint
outer bend zone and inner bend zone are configured to provide a radius of
curvature at an interface of the substrate and the template that
accelerates filling of polymerizable material between the substrate and
the template during the imprinting step.

10. The nano-imprint lithography method of claim 5, wherein during
separation of the template and the patterned layer, the pump system
provides the separation outer bend zone in a vacuum state and the back
pressure zone in a pressure state such that the template has the second
free span length.

11. The nano-imprint lithography method of claim 10, wherein during
separation of the template and the patterned layer, the imprint outer
bend zone and the inner bend zone is deactivated.

12. The nano-imprint lithography method of claim 1, wherein the substrate
is coupled to a substrate chuck, and during the separation step, the
substrate chuck is in a vacuum state.

13. A nano-imprint lithography method, comprising:positioning a template
in superimposition with a substrate defining a volume between the
template and the substrate, the template coupled to a chuck having an
imprint outer bend zone, an inner bend zone, a back pressure zone and a
separation outer bend zone;depositing polymerizable material in the
volume;activating the imprint outer bend zone, the inner bend zone and
the back pressure zone such that template forms a toroidal imprint shape
having a first free span length;positioning the template in contact with
the polymerizable material;solidifying the polymerizable
material;activating the separation outer bend zone and back pressure zone
and deactivating the imprint outer bend zone and the inner band zone such
that template forms a single wave having a second free span length;
and,separating the template from the patterned layer.

14. The nano-imprint lithography method of claim 13, wherein activating
the imprint outer bend zone, the inner bend zone and the back pressure
zone includes providing the imprint outer bend zone and inner bend zone
in a vacuum state and the back pressure zone in a pressure state.

15. The nano-imprint lithography method of claim 13, activating the
separation outer bend zone and back pressure zone includes providing
separation outer bend zone in a vacuum state and back pressure zone in a
pressure state.

16. The nano-imprint lithography method of claim 13, wherein initial
contact of the template with the polymerizable material is at
approximately the middle radius of the substrate.

17. The nano-imprint lithography method of claim 16, wherein droplets of
polymerizable material are deposited on the substrate and volume between
the droplets of polymerizable material define gas passages through which
gas is pushed to an edge of the substrate.

18. The nano-imprint lithography method of claim 13, wherein deactivating
the imprint outer bend zone and the inner band zone includes providing
the zones in an open state.

19. The nano-imprint lithography method of claim 13, wherein the second
free span length is greater than the first free span length.

20. A chuck, comprising:an inner bend zone;a back pressure zone cincturing
the inner bend zone;an imprint outer bend zone cincturing the back
pressure zone, the imprint outer bend zone configured to provide a first
free span length during imprinting; anda separation outer bend zone
cincturing the imprint outer bend zone, the separation outer bend zone
configured to provide a second free span length during separation,
wherein the magnitude of the second free span length is approximately
three times the magnitude of the first free span length.

Description:

CROSS-REFERENCE TO RELATED APPLICATION

[0001]The present application claims priority to U.S. Provisional
Application No. 61/218,686, filed on Jun. 19, 2009, which is hereby
incorporated by reference in its entirety.

BACKGROUND INFORMATION

[0002]Nano-fabrication includes the fabrication of very small structures
that have features on the order of 100 nanometers or smaller. One
application in which nano-fabrication has had a sizeable impact is in the
processing of integrated circuits. The semiconductor processing industry
continues to strive for larger production yields while increasing the
circuits per unit area formed on a substrate, therefore nano-fabrication
becomes increasingly important. Nano-fabrication provides greater process
control while allowing continued reduction of the minimum feature
dimensions of the structures formed. Other areas of development in which
nano-fabrication has been employed include biotechnology, optical
technology, mechanical systems, and the like.

[0003]An exemplary nano-fabrication technique in use today is commonly
referred to as imprint lithography. Exemplary imprint lithography
processes are described in detail in numerous publications, such as U.S.
Patent Publication No. 2004/0065976, U.S. Patent Publication No.
2004/0065252, and U.S. Pat. No. 6,936,194, all of which are hereby
incorporated by reference herein.

[0004]An imprint lithography technique disclosed in each of the
aforementioned U.S. patent publications and patent includes formation of
a relief pattern in a formable (polymerizable) layer and transferring a
pattern corresponding to the relief pattern into an underlying substrate.
The substrate may be coupled to a motion stage to obtain a desired
positioning to facilitate the patterning process. The patterning process
uses a template spaced apart from the substrate and a formable liquid
applied between the template and the substrate. The formable liquid is
solidified to form a rigid layer that has a pattern conforming to a shape
of the surface of the template that contacts the formable liquid. After
solidification, the template is separated from the rigid layer such that
the template and the substrate are spaced apart. The substrate and the
solidified layer are then subjected to additional processes to transfer a
relief image into the substrate that corresponds to the pattern in the
solidified layer.

BRIEF DESCRIPTION OF DRAWINGS

[0005]So that the present invention may be understood in more detail, a
description of embodiments of the invention is provided with reference to
the embodiments illustrated in the appended drawings. It is to be noted,
however, that the appended drawings illustrate only typical embodiments
of the invention, and are therefore not to be considered limiting of the
scope.

[0006]FIG. 1 illustrates a simplified side view of a lithographic system
including a prior art chucking system.

[0007]FIG. 2 illustrates a top down view of a substrate.

[0008]FIG. 3 illustrates a simplified side view of the substrate shown in
FIG. 1 having a patterned layer positioned thereon.

[0009]FIG. 4 illustrates a simplified side view of the prior art chucking
system illustrated in FIG. 1.

[0010]FIG. 5 illustrates a chucking system in accordance with an
embodiment of the present invention having multiple free span zones.

[0011]FIG. 6 illustrates a chucking system in accordance with an
embodiment of the present invention.

[0012]FIG. 7 illustrates the chucking system of FIG. 6 prior to
imprinting.

[0013]FIG. 8 illustrates the chucking system of FIG. 6 during imprinting.

[0014]FIG. 9 illustrates the chucking system of FIG. 6 prior to
separation.

[0015]FIG. 10 illustrates a flow chart of a method for imprinting
polymerizable material on a substrate in accordance with an embodiment of
the present invention.

DETAILED DESCRIPTION

[0016]Referring to the figures, and particularly to FIGS. 1 and 2,
illustrated therein is a lithographic system 10 used to form a relief
pattern on substrate 12. Substrate 12 may have a circular shape; however,
it should be noted substrate 12 may have any geometric shape. For
example, substrate 12 may have a disk shape having an inner radius
r1 and an outer radius r2, with radius r1 being less than
outer radius r2. Further defined between inner radius r1 and
outer radius r2 may be a middle radius r3. Middle radius
r3 may be positioned substantially equidistant from inner radius
r1 and outer radius r2.

[0017]Substrate 12 may be coupled to substrate chuck 14. As illustrated,
substrate chuck 14 is a vacuum chuck. Substrate chuck 14, however, may be
any chuck including, but not limited to, vacuum, pin-type, groove-type,
electrostatic, electromagnetic, and/or the like. Exemplary chucks are
described in U.S. Pat. No. 6,873,087, which is hereby incorporated by
reference herein.

[0018]Substrate 12 and substrate chuck 14 may be further supported by
stage 16. Stage 16 may provide motion along the x, y, and z axes. Stage
16, substrate 12, and substrate chuck 14 may also be positioned on a base
(not shown).

[0019]Spaced-apart from substrate 12 is template 18. Template 18 may
include mesa 20 extending therefrom towards substrate 12, mesa 20 having
a patterning surface 22 thereon. Further, mesa 20 may be referred to as
mold 20. Alternatively, template 18 may be formed without mesa 20.

[0020]Template 18 and/or mold 20 may be formed from such materials
including, but not limited to, fused-silica, quartz, silicon, organic
polymers, siloxane polymers, borosilicate glass, fluorocarbon polymers,
metal, hardened sapphire, and/or the like. As illustrated, patterning
surface 22 comprises features defined by a plurality of spaced-apart
recesses 24 and/or protrusions 26, though embodiments of the present
invention are not limited to such configurations. Patterning surface 22
may define any original pattern that forms the basis of a pattern to be
formed on substrate 12.

[0021]System 10 may further comprise fluid dispense system 32. Fluid
dispense system 32 may be used to deposit polymerizable material 34 on
substrate 12. Polymerizable material 34 may be positioned upon substrate
12 using techniques such as drop dispense, spin-coating, dip coating,
chemical vapor deposition (CVD), physical vapor deposition (PVD), thin
film deposition, thick film deposition, and/or the like. Polymerizable
material 34 may be disposed upon substrate 12 before and/or after a
desired volume is defined between mold 20 and substrate 12 depending on
design considerations. Polymerizable material 34 may comprise a monomer
mixture as described in U.S. Pat. No. 7,157,036 and U.S. Patent
Publication No. 2005/0187339, both of which are hereby incorporated by
reference herein.

[0022]Referring to FIGS. 1 and 3, system 10 may further comprise energy
source 38 coupled to direct energy 40 along path 42. Imprint head 30 and
stage 16 may be configured to position template 18 and substrate 12 in
superimposition with path 42. System 10 may be regulated by processor 54
in communication with stage 16, imprint head 30, fluid dispense system
32, and/or source 38, and may operate on a computer readable program
stored in memory 56.

[0023]Either imprint head 30, stage 16, or both vary a distance between
mold 20 and substrate 12 to define a desired volume therebetween that is
filled by polymerizable material 34. For example, imprint head 30 may
apply a force to template 18 such that mold 20 contacts polymerizable
material 34. After the desired volume is filled with polymerizable
material 34, source 38 produces energy 40, e.g., ultraviolet radiation,
causing polymerizable material 34 to solidify and/or cross-link
conforming to a shape of surface 44 of substrate 12 and patterning
surface 22, defining patterned layer 46 on substrate 12. Patterned layer
46 may comprise a residual layer 48 and a plurality of features shown as
protrusions 50 and recessions 52, with protrusions 50 having a thickness
t1 and residual layer having a thickness t2.

[0024]The above-mentioned system and process may be further employed in
imprint lithography processes and systems referred to in U.S. Pat. No.
6,932,934, U.S. Patent Publication No. 2004/0124566, U.S. Patent
Publication No. 2004/0188381, and U.S. Patent Publication No.
2004/0211754, each of which is hereby incorporated by reference herein.

[0025]As mentioned above, a distance between mold 20 and substrate 12 may
be varied such that a desired volume may be defined therebetween with the
desired volume capable of being filled with polymerizable material 34.
Furthermore, after solidification, polymerizable material 34 may conform
to the shape of the surface of substrate 12 to define patterned layer 46.
In the volume defined between droplets of polymerizable material 34 on
substrate 12, there may be gases present, and as such, droplets of
polymerizable material 34 are generally spread over substrate 12 so as to
avoid, if not prevent, trapping of gases and/or gas pockets in the volume
between substrate 12 and mold 20. Gas and/or gas pockets may result in
pattern distortion of features formed in patterned layer 46, low fidelity
of features formed in patterned layer 46, and/or non-uniform thickness
t2 of residual layer 48.

[0026]Toroidal imprinting of substrate 12 may provide a method of
expelling gas between substrate 12 and mold 20. For example, FIGS. 1 and
4 illustrate a prior art embodiment of chuck 28 capable of altering the
shape of template 18. Chuck 28 is further described in U.S. patent
application Ser. No. 11/749,909, which is hereby incorporated by
reference herein in its entirety. The shape of template 18 may be altered
by chuck 28 such that the distance defined between mold 20 and substrate
12 at middle radius r3 of substrate 12 (shown in FIG. 2) may be less
than the distance defined between mold and substrate at remaining
portions of mold 20. For example, by controlling pressure within chambers
60a-60c of chuck 28, portions of template 18 may bow away from substrate
12 while other portions of template 18 may bow toward substrate 12. In
one example, pressure may be controlled by pressurizing chamber 60b and
providing vacuum force in chambers 60a and 60c. By controlling pressure
to bow template 18, a portion of mold 20 (e.g., portion in
superimposition with middle radius r3 of substrate 12) contacts a
sub-portion of droplets of polymerizable material 34 deposited on
substrate 12. This may cause droplets to spread and may provide a
contiguous film of polymerizable material 34.

[0027]The edge of the contiguous film may define a liquid-gas interface
functioning to push gases toward the edge of substrate 12. Volume between
droplets of polymerizable material 34 define gas passages through which
gas may be pushed to the edge of substrate 12. As a result, the
liquid-gas interface in conjunction with the gas passages may minimize,
if not prevent, trapping of gases in the contiguous film.

[0028]Referring to FIGS. 2 and 4, to control the initial contact of mold
20 at middle radius r3 and maintain a constant fluid front velocity
toward the inner radius r1 and outer radius r2, generally
pressure control within chuck 28 may need to be sized and located such
that deflection of template 18 is symmetric about middle radius r3.
This may reduce the free span length w1 of template 18. Free span
length w1 may be defined as the length of template 18 unsupported by
chuck 28 and substrate 12 (i.e. distance between the last constraint of
template 18 on chuck 28 and edge of patterned layer 46 on substrate 12).
A reduced free span length w1 may increase the separation force,
which is generally undesirable.

[0029]FIGS. 5 and 6 illustrate a chuck 128 in accordance with the present
invention. Chuck 128 provides for a second free span length w2 prior
to separation that is different from the first free span length w1
during imprinting (needed to maintain middle radius r3 contact and
substantially uniform fluid front control). For example, as illustrated
in FIG. 5, the magnitude of second free span length w2 may be larger
than first free span length w1. The larger free span length prior to
separation may reduce the magnitude of force needed to separate template
18 from substrate 12.

[0030]Chuck 128 may include first 66 and second 68 sides. First side 66
may include recesses 70a-70d and supports 72a-72d. Chambers 62a-62d may
be defined by recesses 70a-70d and positioning of template 18 on supports
72a-72d as illustrated in FIG. 6. For example, recesses 70a, supports 72a
and 72b, and a portion of template 18 define chamber 62a. Recesses 70b
and another portion of template 18 define chamber 62b. Generally,
chambers 62a-62d provide four distinct zones, a separation outer bend
zone Z1, an imprint outer bend zone Z2, a back pressure zone
Z3, and an inner bend zone Z4. The separation outer bend zone
Z1 cinctures the imprint outer bend zone Z2, which cinctures
the back pressure zone Z3, which cinctures the inner bend zone
Z4.

[0031]In one embodiment, dimensions of inner bend zone Z4, back
pressure zone Z3 and outer bend zone Z2 may be substantially
similar to dimensions of prior art chucks such as those described in U.S.
patent application Ser. No. 11/749,909, which is hereby incorporated by
reference herein in its entirety. In contrast, separation outer bend zone
Z1 may be configured with an increased diameter as compared to outer
zones of prior art chucks to provide second free span length w2
during separation. Second free span length w2 may be approximately
three times free span length w1. For example, free span length
w1 is generally about 2.5 mm. Separation outer bend zone Z1 may
be configured with an increased diameter as compared to outer zones of
prior art chucks to provide second free span length w2 during
separation of about 14 mm.

[0032]In one example, inner bend zone Z4 may have a diameter of
approximately 18 mm. Back pressure zone Z3 may extend from
approximately 19 mm to approximately 67 mm. Imprint bend zone Z2 may
extend from approximately 68 mm to approximately 90 mm, and separation
bend zone Z1 may extend from approximately 91 mm to approximately
117 mm. It should be noted that extension of separation outer bend zone
Z1 and dimensions of zones Z1-3 may be determined based on size
and configuration of template 18.

[0033]A pump system may operate to control pressure within each zone
Z1-Z4. Pump system may be in fluid communication with
throughways. In one embodiment, a single pump system may operate to
control pressure within each zone Z1-Z4. Alternatively, two or
more pump systems may operate to control pressure within each zone
Z1-Z4. Pressure may include application of pressure (i.e.,
pressure state) within zones Z1-Z4 and/or application of vacuum
force (i.e., vacuum state) within zones Z1-Z4. Generally,
pressure state may be between approximately 0 to 10 kPa and vacuum state
may be between approximately 0 to -90 kPa.

[0034]FIG. 7 illustrates use of chuck 128 prior to imprinting. Prior to
imprinting, pump system may provide imprint outer bend zone Z2 and
inner bend zone Z4 in a vacuum state. Vacuum state of outer bend
zone Z2 and inner bend zone Z4 may be substantially similar.
Alternatively, magnitude of vacuum state of outer bend zone Z2 may
be increased as compared to inner bend zone Z4 or magnitude of
vacuum state of outer bend zone Z3 may be decreased as compared to
inner bend zone Z4.

[0035]Prior to imprinting, back pressure zone Z3 may be provided in a
pressure state. Having outer bend zone Z2 and inner bend zone
Z4 in a vacuum state and back pressure zone Z3 in a pressure
state provides template 18 in a toroidal imprint shape as illustrated in
FIG. 7. The toroidal imprint shape provides template 18 with a first free
span length w1. Magnitude of free span length w1 may be between
approximately 1.5 mm-4 mm. For example, magnitude of free span length
w1 may be 2.5 mm.

[0036]Prior to and/or during imprinting, separation outer bend zone
Z1 may be deactivated in an open and/or blocked state. FIG. 6
illustrates separation outer bend zone Z1 in a blocked state wherein
no pressure or vacuum is applied to chamber 70a by pump system. FIG. 7
illustrates separation outer bend zone Z1 in an open state wherein
chamber 70a is open in that template 18 only contacts support 72b.
Alternatively, separation outer bend zone Z1 may be provided in a
pressure state, however, at significantly a lower pressure state as
compared to back pressure zone Z3, or separation outer bend zone
Z1 may be provided in a vacuum state that is significantly lower
than imprint outer bend zone Z2 and/or inner bend zone Z4.

[0037]Referring to FIGS. 2 and 8, the toroidal imprint shape created prior
to imprinting may provide deflection of template 18 symmetric about
middle radius r3 of substrate 12 during imprinting. Vacuum state and
positioning of imprint outer bend zone Z2 and inner bend zone
Z4 (e.g., about the middle radius r3) may be configured to
provide a radius of curvature at the interface of substrate 12 and
template 18 that accelerates filling of polymerizable material 34. Radius
of curvature may be on the order of 800 mm to 8000 mm.

[0038]Referring to FIG. 9, during separation of template 18 and substrate
12 (e.g., patterned layer 46 shown in FIG. 2), separation outer bend zone
Z1 and back pressure zone Z3 may be activated and imprint outer
bend zone Z2 and the inner bend zone Z4 may be deactivated
providing template 18 with a single wave having free span length w2.
For example, separation outer bend zone Z1 may be activated to be in
a vacuum state and back pressure zone Z3 may be activated to be in a
pressure state while imprint outer bend zone Z2 and the inner bend
zone Z4 may be deactivated in a blocked state. Alternatively,
imprint outer bend zone Z2 and/or inner bend zone Z4 may be
activated in a minimal pressure state.

[0039]Activation of separation outer bend zone Z1 and back pressure
zone Z3 with minimal or no interaction with imprint outer bend zone
Z2 and the inner bend zone Z4 alters the first free span length
w1 to a second free span length w2. An increase from the first
free span length w1 to the second free span length w2 minimizes
separation force. The increase in free span length w2 may amplify an
upward separation force generally provided during separation of template
18 and substrate 12, and as such, may provide a larger crack angle for
the same upward force as compared to free span length w1. This may
reduce the force needed to separate template 18 from substrate 12. For
example, first free span length w1 of approximately 2.5 mm may
provide a crack angle of approximately 0.8 mrad. Providing second free
span length w2 of approximately 14 mm may provide a crack angle of
approximately 3.1 mrad. For chuck 128, crack angle may thus be greater
than approximately 1.5 mrad reducing separation force by greater than
approximately 40% as compared to providing free span length w1
during separation.

[0040]In one embodiment, as illustrated in FIG. 9, in addition to the
increase from the first free span length w1 to the second free span
length w2, vacuum state of substrate chuck 26 may be increased
during separation. Generally, substrate chuck 26 is always in a vacuum
state (e.g., -5 kPa) in order to hold substrate 12 during imprinting.
Increasing vacuum state of substrate chuck 26 during separation may aid
in retaining substrate 12 during separation. For example, vacuum state
may be increased to approximately -20 kPa during separation.

[0041]FIG. 10 illustrates a flow chart for a method 100 for imprinting
polymerizable material 34 on substrate 12. In a step 102, template 18 may
be coupled to chuck 28b. In a step 104, template 18 may be positioned in
superimposition with substrate 12 defining a volume between template 18
and substrate 12. In a step 106, polymerizable material 34 may be
deposited in the volume defined between template 18 and substrate 12. In
a step 108, pump system may activate imprint outer bend zone Z2,
inner bend zone Z4, and back pressure zone Z3 creating a
toroidal imprint shape having free span length w1. For example, pump
system may provide imprint outer bend zone Z2 and inner bend zone
Z4 in a vacuum state and back pressure zone Z3 in a pressure
state. In a step 110, template 18 may contact polymerizable material 34.
In a step 112, polymerizable material may be solidified. In a step 114,
pump system may activate separation outer bend zone Z1 and back
pressure zone Z3, and deactivate imprint outer bend zone Z2 and
the inner bend zone Z4 to provide template 18 with a single wave
having free span length w2. For example, pump system may provide
separation outer bend zone Z1 in a vacuum state and back pressure
zone Z3 in a pressure state while outer bend zone Z2 and the
inner bend zone Z4 are deactivated (e.g. blocked). In addition, pump
system may increase vacuum state of substrate chuck 26. For example, pump
system may increase vacuum state of substrate chuck 26 from approximately
-5 kPa to approximately -20 kPa. In a step 116, template 18 may be
separated from at least a portion of patterned layer 46. In one example,
template 18 may be completely separated from the patterned layer 46.